UDP-glycosyltransferases (UGTs) constitute the largest glycosyltransferase family in the plant kingdom,regulating many metabolic processes by transferring sugar moieties onto various small molecules. How-ever, their p...UDP-glycosyltransferases (UGTs) constitute the largest glycosyltransferase family in the plant kingdom,regulating many metabolic processes by transferring sugar moieties onto various small molecules. How-ever, their physiological significance in plants remains largely unknown. Here, we reveal the functionsand mechanisms of two Arabidopsis UGT genes, UGT73C3 and UGT73C4, which are strongly induced byPseudomonas syringae pv. tomato (Pst) DC3000. Overexpression of these genes significantly enhancedplant immune response, whereas their loss of function in double mutants led to increased sensitivity topathogen infections. However, single mutants showed no obvious alteration in pathogen resistance. Tofurther investigate the regulatory mechanisms of UGT73C3/C4 in plant immunity, we conducted compre-hensive secondary metabolome analyses and glycoside quantification. Overexpression lines accumulatedhigher levels of pinoresinol diglucosides than wild-type plants, both before and after Pst DC3000 treatment,whereas double mutants accumulated lower levels. Furthermore, in vitro and in vivo experiments demon-strated that UGT73C3 and UGT73C4 can glycosylate pinoresinol to form pinoresinol monoglucoside anddiglucoside. Moreover, pinoresinol glycosylation promotes the plant immune response by increasing reac-tive oxygen species production and callose deposition. Additionally, the transcription factor HB34 wasfound to activate UGT73C3 and UGT73C4 transcription and play a key role in plant immunity. Overall,this study reveals a novel pathway in which UGT73C3/C4-mediated pinoresinol glycosylation, regulatedby HB34, enhances the plant immune response.展开更多
文摘UDP-glycosyltransferases (UGTs) constitute the largest glycosyltransferase family in the plant kingdom,regulating many metabolic processes by transferring sugar moieties onto various small molecules. How-ever, their physiological significance in plants remains largely unknown. Here, we reveal the functionsand mechanisms of two Arabidopsis UGT genes, UGT73C3 and UGT73C4, which are strongly induced byPseudomonas syringae pv. tomato (Pst) DC3000. Overexpression of these genes significantly enhancedplant immune response, whereas their loss of function in double mutants led to increased sensitivity topathogen infections. However, single mutants showed no obvious alteration in pathogen resistance. Tofurther investigate the regulatory mechanisms of UGT73C3/C4 in plant immunity, we conducted compre-hensive secondary metabolome analyses and glycoside quantification. Overexpression lines accumulatedhigher levels of pinoresinol diglucosides than wild-type plants, both before and after Pst DC3000 treatment,whereas double mutants accumulated lower levels. Furthermore, in vitro and in vivo experiments demon-strated that UGT73C3 and UGT73C4 can glycosylate pinoresinol to form pinoresinol monoglucoside anddiglucoside. Moreover, pinoresinol glycosylation promotes the plant immune response by increasing reac-tive oxygen species production and callose deposition. Additionally, the transcription factor HB34 wasfound to activate UGT73C3 and UGT73C4 transcription and play a key role in plant immunity. Overall,this study reveals a novel pathway in which UGT73C3/C4-mediated pinoresinol glycosylation, regulatedby HB34, enhances the plant immune response.
